Information Disclosure in mechanize (CVE-2026-107715)
Summary
Vulnerability in mechanize (CVE-2026-107715). Confidential information can be exposed externally. Exploitable via mechanize. Mitigation: upgrade to 2.14.1 or later.
Original description
The description as published by the source.
Summary
mechanize leaked credentials to the redirect target when an HTTP redirect crossed to another host. Credentials set through Mechanize#request_headers= leaked even when they were Authorization.
Details
Two defects, both in lib/mechanize/http/agent.rb.
1. Mechanize#request_headers= bypassed the redirect strip entirely. #request_add_headers copied @request_headers onto every request unconditionally, with no host check, including the request issued after a redirect. The strip in #response_redirect mutated only the per-request headers hash and never touched agent state. Because request_headers= is the documented way to set a default credential for every request, the header the code explicitly protected — Authorization — was the one most likely to leak.
2. The strip list omitted Proxy-Authorization and Cookie2. Only CREDENTIAL_HEADERS = ['Authorization'] and COOKIE_HEADERS = ['Cookie'] were removed from the per-request headers hash on a cross-host redirect.
Cookies held in Mechanize#cookie_jar and credentials held in Mechanize::HTTP::AuthStore are not affected. Both are looked up per-URI, so they never follow a redirect to a foreign host. The exposure was limited to headers the caller set by hand.
PoC
agent = Mechanize.new
agent.request_headers = { 'Authorization' => 'Bearer secret' }
agent.get('https://example.test/redirects-to-attacker')
# the request to the attacker's host carries "Authorization: Bearer…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-107715 has been found in mechanize.
Attackers can target a specific entry point like mechanize over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.8/10.
What to do: upgrade mechanize to 2.14.1 or later.
If unsure, ask your IT team or search "mechanize CVE-2026-107715" on the vendor's site.
CVE-2026-107715 (mechanize) — CWE-200 / CVSS v3 6.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: mechanize / Authorization / Cookie2 / headers
Patched: 2.14.1 — apply immediately
Workaround: Set Mechanize#redirect_ok = false and handle redirects explicitly, or avoid request_headers= for credentials and pass them per-request only to hosts you intend to authenticate to.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Information disclosure (CWE-200) exists in mechanize. Attackers reach the vulnerable code path via mechanize without authentication.
Check the vendor advisory for the affected versions of mechanize. Attack surface: mechanize / Authorization / Cookie2 / headers.
Severity: Medium (CVSS 6.8/10). Confidential information can be exposed externally.
Update to 2.14.1.
Workaround: Set Mechanize#redirect_ok = false and handle redirects explicitly, or avoid request_headers= for credentials and pass them per-request only to hosts you intend to authenticate to.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'mechanize' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'mechanize' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
mechanizeを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Set `Mechanize#redirect_ok = false` and handle redirects explicitly, or avoid `request_headers=` for credentials and pass them per-request only to hosts you intend to authenticate to.パッチが適用されるまでの応急処置として、Set
Mechanize#redirect_ok = falseand handle redirects explicitly, or avoidrequest_headers=for credentials and pass them per-request only to hosts you intend to authenticate to. を実施。回避策の副作用 (機能低下) を確認した上で。 -
3Apply patch patch
Upgrade mechanize to 2.14.1ステージング環境で 2.14.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。